JP2002522597A - Continuous gas phase coating of polymerization catalyst - Google Patents

Abstract

A continuous process for gas phase coating of polymerization catalyst. The polymerization catalyst is introduced in a gas phase plug flow type reactor wherein it is submitted to polymerization conditions in the presence of at least one monomer such that at least 95% by weight of the produced coated catalysts have a coating yield comprised between 0.5 to 2 times the average coating yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an on-line continuous gas-phase coating method for a polymerization catalyst. The invention further relates to a continuous gas-phase fluidized-bed process for the production of polyolefins (more particularly polyethylene) with improved levels of productivity without fouling, the process comprising the continuous gas-phase coating process according to the invention. It consists of introducing the coating polymerization catalyst obtained.

In fluidized-bed polymerization of olefins, the polymerization is carried out in a fluidized-bed reactor, in which a bed of polymer particles is kept fluid by an ascending gas stream of gaseous reactive monomers. The initiation of this type of polymerization generally employs a bed of polymer particles similar to the polymer desired to be produced. During the course of the polymerization, fresh polymer is generated by the catalytic polymerization of the monomer and the polymer product is withdrawn to maintain the bed at a more or less constant volume. An industrially preferred method uses a fluidizing grid to distribute the fluidizing gas to the bed and to act as a bed support when the gas supply is shut off. Product polymer is generally withdrawn from the reactor via a discharge conduit located near the fluidization grid at the bottom of the reactor. The fluidized bed consists of a bed of growing polymer particles, polymer product particles and catalyst particles. The bed is kept fluid by a continuous upward flow of fluidizing gas from the bottom of the reactor, the fluidizing gas being composed of circulating gas from the top of the reactor and make-up feed. The fluidizing gas flows into the bottom of the reactor and preferably reaches the fluidized bed via a fluidizing grid.

[0003] The polymerization of olefins is an exothermic reaction and therefore means must be provided to cool the bed and remove the heat of polymerization. In fluidized bed polymerization of olefins, the preferred method of removing the heat of polymerization is to supply a gas to the polymerization reactor (i.e., a fluidizing gas at a temperature lower than the desired polymerization temperature) and pass the gas through the fluidized bed to produce a heat of polymerization. By removing the gas from the reactor and cooling it by passing it through an external heat exchanger and circulating it through the bed. The temperature of the circulating gas can be adjusted with a heat exchanger to maintain the fluidized bed at the desired polymerization temperature. In this process for the polymerization of α-olefins, the recycle gas generally consists of monomeric olefins, which, if desired, can be converted to nitrogen and / or lower alkanes, such as ethane, propane, butane, pentane, hexane and / or hydrogen, for example hydrogen. Combine with gaseous chain transfer agent. The circulating gas thus supplies monomer to the bed, fluidizes the bed, and serves to maintain the bed at the desired temperature. The monomers consumed by the polymerization reaction are generally replenished by adding make-up gas to the circulating gas stream.

[0004] The production rate in a commercial gas fluidized bed reactor of the type described above (ie the space-time yield in terms of the weight of polymer produced per unit volume of reactor space per unit time) can remove heat from the reactor. It is well known that it is limited by the maximum speed.
The heat removal rate can be increased, for example, by increasing the velocity of the circulating gas and / or decreasing the temperature of the circulating gas and / or changing the heat capacity of the circulating gas. However, there are limits to the speed of circulating gas that can be used in industrial practice.
Beyond this limit, the bed becomes unstable or lifts out of the reactor in the gas stream, causing blockage of the circulation line and damage to the circulation gas compressor or blower. Furthermore, there is a limit to the extent to which the circulating gas can be practically cooled. This is primarily determined by economic considerations and is practically generally determined by the temperature of the industrial cooling water available on site. Refrigeration can also be used if desired, but this increases production costs. Thus, in industrial practice, the use of cooling cycle gas as the only means of removing heat of polymerization from gas fluidized bed polymerization of olefins has the disadvantage of limiting the maximum production rate obtained.

[0005] The prior art is disclosed, for example, in EP 89691, EP 173261, WO 94/25.
No. 495, US Pat. No. 5,352,749, US Pat. No. 5,436,304, WO96 /
A number of methods have been suggested to increase the heat removal capacity of the circulating stream, such as 04321 and WO 94/28032, the contents of which are incorporated herein by reference.

[0006] The above disclosed methods all contribute to increasing the level of productivity obtained in the fluidized bed polymerization process, which is also one of the objects according to the present invention. However, it is known in the art that the major problem encountered in these high productivity polymerization processes is the fouling phenomenon that can occur at any point in the reactor.

One of the major problems encountered in fluidized bed processes for producing polyethylene and ethylene copolymers is reactor fouling (commonly referred to in the literature). In particular, the use of catalyst systems which exhibit increasingly higher activity at the start of the polymerization tends to adversely affect this fouling phenomenon. Today, this problem is exacerbated on an industrial scale, where the production capacity of the polymerization reactor tends to increase, for example, for industrial ethylene fluidized bed polymerization where more than 350 kT of polyethylene can be achieved in a single reactor each year. I do.

[0008] The problem of fouling or agglomerates is very high because the agglomerates can grow very large before loosening and falling into the fluidized bed. When dropped into the main fluidized bed, they can interfere with powder fluidization, circulation and withdrawal. If powder withdrawal is delayed or the beds coalesce, reactor production must be stopped and the reaction vessel must be opened for cleaning. This is a very expensive production expense.

There is a great deal of consideration in the prior art for a clear explanation of these pollution phenomena, as well as their many different occurrences. It is often said that the type of catalyst used causes contamination. Static electricity has also been shown to be the cause. Furthermore, operating conditions are considered as the most important criteria. In fact, those skilled in the art have developed a number of different theories and proposals that attempt to explain and reduce pollution phenomena.
All of these pollution phenomena would be a significant improvement in the art if any explanation for their occurrence could be significantly reduced or eliminated.

The Applicant has now unexpectedly found that the contamination problems commonly encountered in the prior art methods described above can be significantly reduced or even eliminated using the method according to the present invention.

This time, the present inventors are easy to implement, can use all types of polymerization catalysts, significantly reduce or even eliminate the potential fouling phenomena in the reactor, and furthermore from the disclosure of the present invention. Obviously we have found a way to bring many other benefits.

[0012] The present invention provides a novel continuous process that allows for improved on-line gas phase coating of polymerization catalysts.

Various prior art publications describe the coating of polymerization catalysts.

EP-622382 discloses propylene / ethylene using a coated catalyst obtained by treating a mixture of a conventional supported heterogeneous Ziegler-Natta catalyst component, an organic-Al cocatalyst and an electron donor with one monomer. A copolymerization is disclosed. Coated catalyst 10:
It has a polymer coating: catalyst weight ratio of less than 1. The use of coated catalysts manufactured off-site or on-site increases randomness without the need for other processes or catalyst system changes.

[0015] EP-588277 discloses a continuous olefin polymerization process, which comprises adding a coated catalyst, the catalyst having a polymer coating with a coating: catalyst weight ratio of less than 10: 1.

[0016] EP-338676 discloses a Ziegler-Natta type catalyst for (co) polymerizing propylene in the form of a preactivated support. Preactivated support is treated with TiCl _4. The treated support is contacted with an alkylaluminum halide and optionally propylene mixed with ethylene and / or C4-C8α-olefin to contain 0.1-10 g of propylene (co) polymer per mole of Ti. A coated catalyst is formed.

[0017] These prior publications disclose a number of different advantages arising from the use of coated catalysts thus prepared. However, Applicants have determined that the use of these prior art coated catalysts does not eliminate the major contamination problems described above.

Thus, according to the invention, the polymerization catalyst is introduced into a gas-phase plug-flow reactor, which, in the presence of at least one monomer, has an average coating yield of at least 95% by weight of the resulting coated catalyst. The present invention provides a continuous gas phase coating method of a polymerization catalyst, which is subjected to polymerization conditions so as to have a coating yield of 0.5 to 2 times of the above.

Plug flow reactors are well known in the art. With regard to flow patterns, plug flow reactors are characterized by their limiting properties without axial mixing. In contrast, there are generally continuous stirred tank reactors that are characterized by their complete mixing limiting properties.

According to the invention, a plug-flow reactor means a reactor which reaches such a limiting characteristic without axial mixing. Accordingly, a continuously stirred tank reactor is specifically excluded from the present invention. With regard to the comparison of the flow patterns, the plug flow reactor according to the invention preferably has at least three continuously stirred tank reactors, more preferably at least four continuously stirred tank reactors, particularly preferably at least five continuously stirred tank reactors. The battery is even.

The plug flow reactor according to the invention is preferably a tubular reactor.

In accordance with the invention, the plug flow reactor is preferably horizontal or slightly inclined at a downward angle formed with respect to a horizontal baseline ideally comprised between 1 and 7 °. The downward angle (from the inlet to the outlet of the reactor) induces improved catalyst flow throughout the reactor via the effect of gravity.

Preferably, it has a substantially circular cross-section including a centrally located drive shaft extending longitudinally through a reactor fitted with a plurality of adjacent paddles. The paddles allow them to substantially cause no backward movement of the particulate matter contained within the reactor, but rather extend laterally and a short distance from the interior surface of the reactor.
The reactor is individually divided into polymerization compartments with adjustable gas composition and a controlled polymerization temperature, and is thus made to regulate the gas intermixing and transfer of particulate matter between said compartments.

The reactor further comprises one or more reactor off-gas outlets along the top portion, one or more steam circulation inlets along the bottom portion, and one or more catalyst addition inlets. One or more additive inlets (eg, quench liquid) and means for removing the resulting coated catalyst may be provided.

The coating method according to the invention can be applied to all types of polymerization catalysts. It has proven to be advantageous for a Ziegler-Natta type catalyst system consisting essentially of a solid catalyst consisting of a compound of a transition metal and a cocatalyst consisting of an organic compound of a metal (ie an organometallic compound, for example an alkylaluminum compound). Was done. Highly active catalyst systems have been known for many years and can produce large quantities of polymer in a relatively short time, thus avoiding the step of removing catalyst residues from the polymer. These highly active catalyst systems generally consist of a solid catalyst consisting primarily of a transition metal complex, a magnesium complex and a halogen-containing complex. An example is US42
60709, EP0598094, EP0099774 and EP017
No. 5532. This method is further described, for example, in WO 9309147.
No., WO9513873, WO9534380 and WO09905187
It is also particularly suitable for use with Ziegler-Natta catalysts supported on silica in No. 1.

This method is described, for example, in EP 0129368, EP 0206794, EP 04
Particularly suitable for use with metallocene type catalysts such as those described in EP 20436 and EP0416815. Highly active catalysts consisting mainly of chromium oxide activated by heat treatment and bound to a particulate support based on a refractory oxide can also be used advantageously, for example as described in EP 0 275 675, EP 0 453 116, WO 99/12978. Something was done.

In addition, late transition metal (eg platinum or palladium) catalyst complexes (eg those described in WO 96/23010) can be used.

[0028] Catalysts such as those described in BP application WO 99/02472 can also be used to advantage.

The catalyst can be introduced into the plug flow reactor in any form (eg, as a slurry) or preferably in a dry state.

The monomers used in the coating process depend on the nature of the subsequent polymerization process.

According to a preferred embodiment of the present invention, the monomer is one or more α-olefins having 2 to 40 carbon atoms, preferably those having 2 to 8 carbon atoms, more preferably It is selected from ethylene and / or propylene and / or butene.

According to the present invention, at least 95% by weight of the resulting coated catalyst has a coating yield comprised between 0.5 and 2 times the average coating yield. The coating yield used herein is defined by the weight ratio of the coated polymerization catalyst to the uncoated polymerization catalyst. The use of the plug flow reactor according to the invention ensures that the polymerization catalyst subjected to the coating process does not substantially flow out of the coating reactor in the non-polymerized form. In fact, the resulting coated polymerization catalyst is characterized by a narrow coating yield distribution. According to a preferred embodiment of the present invention, the efficiency of the plug flow reactor is such that there is a substantially uncoated polymerization catalyst exhibiting a coating yield of less than 20% of the average coating yield. Similarly, an average coaching yield of 1
It is also preferred that a substantially uncoated polymerization catalyst exhibiting a coating yield of greater than 80% is present.

The plug flow reactor according to the invention is characterized by a narrow residence time distribution of the coated polymerization catalyst.
According to a preferred embodiment of the present invention, more than 90% by weight of the coated polymerization catalyst has a residence time comprised between 0.7 and 1.8 times the average residence time. Preferably, there is a substantially uncoated polymerization catalyst exhibiting a residence time of less than 35% of the average residence time.

When using the coated polymerization catalyst obtained according to the invention in a continuous polymerization process, the applicant has surprisingly found that the pollution problems previously experienced can be solved, especially for continuous gas-phase polymerizations.

Without being limited only by the following description, Applicants believe that one of the reasons behind this success stems from the narrow coating yield distribution characteristics exhibited by the coated polymerization catalysts according to the present invention.

For example, active growing polymers in fluidized bed polyolefin reactors are known to be composed of a wide range of particle sizes. That is, the powder is said to have a broad particle size distribution. Some of the reasons for this broad legal distribution are the size range of the initial catalyst particles charged to the reactor, differences in catalytic activity of each catalyst particle, differences in residence time of each growing polymer particle, and aggregation of polymer particles. . It is believed that the narrow coating yield distribution profile exhibited by the coated polymerization catalysts according to the present invention has a significant effect on the particle size distribution of the resulting polymer, thus eliminating fouling phenomena.

For example, when using a coated catalyst in a gas-phase reactor, on-line coating in a plug-flow reactor has the following general advantages independently of the catalyst system used: Dry catalyst injection only (no solvent) Α-olefin (C6)
Of the polymerization of or copolymerization with it, for example a smooth reaction with control kinetics (no initial particle overheating and good morphology control) using control parameters such as low monomer partial pressure and low reaction temperature, higher than 300 KTPA small reactor volume required to supply a large scale plant (0.5 m ³ below) low residence time with (1 hour or less), a plug flow reactor (equivalent to 6 to 8 continuous stirred tank reactor) Control of the particle residence time without ungrown catalyst particles from the main reactor, reduced with the possible additional benefit of the antistatic agent introduced during the coating process, the static electricity at the point of injection in the polymerization reactor, e.g. Easily reduce hot spots with active catalyst Dispersion of coated catalyst in a fluidized bed, rate profile by adding a small fraction of activator Allows for better control and increase of the final polymerization yield, smooth stirring (low rotation speed) and low gas velocities which give good entrainment at the end with low entrainment and better morphology . The use of on-line gas-phase coating of the catalyst further allows: to modify the initial velocity profile to allow the catalyst to disperse before reaching its peak activity, thus homogenizing the velocity profile Can be coated in the gas phase to avoid catalyst modification and morphological involvement observed in slurries.Possibility to spray anti-static and catalyst activator into solution.Target melt index range with ethylene flow control and comonomer control. (
Smooth control of the initial reaction at low ethylene pressure and temperature) There is the ability to increase final polymer yield and reduce residence time (higher reactor capacity) Cocatalyst usage and per ton・ Easier transition between Ziegler and metallocene catalysts ・ Improves plant reliability and facilitates access to large, efficient and flexible plants .

The coating process according to the invention is ideally integrated upstream of a conventional industrial gas-phase polymerization process similar to the gas-phase polyethylene process of BP Chemicals, for example, in which the coating catalyst is supplied in a continuous manner in a gas-phase reactor. It is.

FIG. 1 is a drawing of an apparatus for gas phase polymerization of olefins according to the present invention. The apparatus comprises a fluidized bed reactor fitted with a top and a bottom, the bottom comprising a fluidization grid, further comprising a cylinder and comprising vertical side walls and a desorption chamber above said cylinder, the reaction gas An inlet chamber for the mixture is located below the grid, and an external circulation conduit for the reactant gas mixture is provided to connect the top of the reactor to the inlet chamber for the reactant gas mixture, and a compressor and at least one exchanger Is provided. The left side of the figure illustrates a plug flow reactor into which the catalyst is injected and from which the coated catalyst flows out and flows into the polymerization reactor.

The process according to the invention is particularly suitable for producing polymers in a continuous gas fluidized bed process. Examples of polymers which can be prepared according to the invention are, for example, EPR (polymer of ethylene and propylene), EPDM (polymer of ethylene copolymerized with propylene and a diene such as, for example, hexadiene, dicyclopentadiene or ethylidene norbornene).

In an advantageous embodiment of the invention, the coated polymerization catalyst is used for the production of polyolefins, preferably copolymers of ethylene and / or propylene and / or butene. Preferred α-olefins used in combination with ethylene and / or propylene and / or butene are those having 4 to 8 carbon atoms. However, small amounts of α-olefins having more than 8 carbon atoms, such as 9 to 40 carbon atoms (eg, conjugated dienes) can be used if desired. That is, it is possible to produce copolymers of ethylene and / or propylene and / or butene with one or more C4-C8α-olefins. Preferred α-olefins are but-1-ene, pent-1-ene, hex-
1-ene, 4-methylpent-1-ene, oct-1-ene and butadiene. Examples of higher olefins which can be copolymerized primarily with ethylene and / or propylene monomers or which can be used as a partial replacement of C4-C8 monomers are dec-1-ene and ethylidene norbornene. According to a preferred embodiment, the process according to the invention preferably comprises the preparation of polyolefins in the gas phase by copolymerization of ethylene with but-1-ene and / or hex-1-ene and / or 4-methylpent-1-ene. Applied to Ethylene or propylene or butene-1 is present as a major component of the monomers, preferably in an amount of at least 70% of the total monomers / comonomer, more preferably at least 80%.

The process according to the invention is preferably a linear low density based on a wide variety of polymer products, for example copolymers of ethylene and but-1-ene, 4-methylpent-1-ene or hex-1-ene. Polyethylene (LLDPE) and, for example, ethylene and a small proportion of higher α-olefins (eg, but-1-ene, pent-1)
-Ene, hex-1-ene or 4-methylpent-1-ene).

This method is particularly suitable for polymerizing polyolefins at an absolute pressure of 0.5 to 6 MPa and a temperature of 30 to 130 ° C. For example, for LLDPE production, the temperature is preferably in the range of 75-90C, and for HDPE the temperature is typically 80-105C depending on the activity of the catalyst used and the desired polymer properties.

Thus, according to a preferred embodiment, the present invention further provides (a) ethylene, (b) propylene, (c) a mixture of ethylene and propylene, (d) butene, and (e) 1
One or more olefin monomers selected from other α-olefins mixed with one or more of the other (a), (b), (c) and (d) are polymerized in a fluidized bed reactor in at least some amount. In the polymerization by continuously circulating a gas stream comprising olefins of some kind in a fluidized bed in the reactor under the reaction conditions in the presence of the coated polymerization catalyst, the method includes introducing the coated polymerization catalyst. The present invention also relates to a continuous gas fluidized bed method obtained by the continuous gas phase coating method of the present invention.

Applicants have unexpectedly found that significant improvements can be obtained by applying the present invention to conventional gas phase fluidized bed polymerization processes.

FIGS. 2 and 3 are diagrams of the apparatus and method according to the present invention. Accordingly, the present invention is not limited to only these particular embodiments.

The catalyst is fed from a F301 vessel to “mini-Ecclesul” (1) and is then introduced with a stream of nitrogen into the bottom of a horizontal plug flow reactor. The flow rate of catalyst introduced into the reactor is regulated by the mini-Ecclesur speed and cross-checked with the weight of the F301 vessel.

The starting powder is preferably initially supplied at start-up to allow good mixing of the small amount of catalyst injected into the reactor and to operate the reactor properly. Injection of ethylene, optional comonomer, hydrogen and nitrogen takes place at the bottom of the reactor. Preferably there are at least three different injection points along the reactor to allow good distribution of the reactants within the reactor. The three flow indicators determine the exact opening of the valve to obtain an equal flow at each injection point. Mixing of the reactants occurs before the line, and the flow rate of each reactant is controlled by a regulatory control system. Suitable comonomers are preferably either butene or hexene. An injection point is provided to continue adding other compounds. The plug flow reactor is preferably a commercial reactor that can feed a 300K TPA gas phase plant. This is equivalent to 10 g of P with about 16 kg / h of catalyst.
E / gcata can be polymerized, for example, with the following internal dimensions: length = 1.88 m diameter = 0.42 m L / D = 4.5

Preferably, normal operating conditions for coating are from 20 to 100 ° C., more preferably 40 ° C.
６０60 ° C. Preferably the normal operating conditions during coating are from 1 to 40 bar,
More preferably, the total pressure (relative) is between 5 and 25 bar. Preferably the normal operating conditions for coating are residence times of 10 minutes to 4 hours, more preferably 40 to 80 minutes. Preferably, the normal operating conditions for coating are a fluidization rate of 3 to 10 cm / s.

Preferably the normal operating conditions for coating are a coating yield of 2 to 100 g of coated catalyst per g of catalyst, more preferably 4 to 20 g of coated catalyst per g of catalyst.

The gas phase is adjusted by adjusting the flow rates of ethylene, comonomer and hydrogen. The pressure can be adjusted by adjusting the nitrogen flow or by opening the flare (after the gas outlet). The temperature is controlled by adjusting the flow rate of the industrial water (30 ° C.) and the steam (90-100 ° C.) in the double envelope of the reactor. If necessary, a heat exchanger can also be used.

A filter with a cartridge is installed to avoid entrained particles flowing into the flare. Entrained particles are recovered into the reactor by a stream of nitrogen that desorbs these particles from the filter cartridge.

The plug flow characteristics of the reactor are mainly obtained by a specially designed stirrer. The stirrer is installed inside the reactor and preferably comprises about 5 to 12 paddle members. FIG.
As shown in (1), one paddle member is composed of four paddles separated by an angle of 90 ° and fixed to a stirring shaft.

The stirrer is driven by a motor and can be operated at different speeds. The reactor-stirrer system is preferably tilted downward (from the inlet to the outlet) by a small angle (1-7 °) to allow a good production process in the reactor. Successive paddles on the stirring shaft are shifted by an angle θ, preferably by 30 to 70 °. The two paddles in the shaft are separated by a distance corresponding to the length of one paddle member plus a clearance of several mm (more preferably 1 to 5 mm).

The paddle is straight, rectangular and perpendicular to the reactor interior surface. The clearance between the paddle and the inner surface of the reactor is a few mm, more preferably 1-5 mm. The main components for reactor design should be made of stainless steel. The coated catalyst is withdrawn at the end of the reactor. The level is ideally kept at about 30-50% and the valves are opened sequentially. Nitrogen is transferred to the sampling nozzle to prevent clogging.

Various nozzles are ideally fitted to the reactor, for example for level control, temperature measurement or control, gas phase analysis, pressure control and water and / or oxygen measurement.

Ideally equipped with several nozzles, an inert carbon, for example pentane,
Allows for the provision of extra material inlets and outlets such as purifying agents, antistatic agents, water and microbial killers. This allows for reactor purification and protection against the reaction effluent. For safety and economic reasons, it is preferred to circulate the outlet gas to the gas supply section. This can be done via a small compressor. The coated catalyst can then be sent to a degasser. A countercurrent flow of nitrogen is circulated upward from the bottom of the degasser. The coated catalyst is then ideally sent to a storage vessel and / or a reactor.

There is also the possibility of continuously releasing the coated catalyst directly into the main polymerization reactor. In this case, the coating reactor is maintained at a slightly higher pressure (2-4 bar) than the polymerization reactor.

The advantages associated with the use of on-line coating technology are discussed below with different specific catalyst systems.

[0060]Conventional prepolymerized Mg / Ti Ziegler-Natta catalyst  The lower constant cost and the inexpensive design without solvent recovery make traditional slurry
Alternative to polymer batch design. 20-50 g to reduce prepolymer yield
/ Mitanium to 5-10 g / mM). Fine through coating reactor circulation loop
Enables control of things. Co-load with significant additional benefits in terms of morphology and product quality
Enable On-line control of coated catalyst is difficult for prepolymer batch sequence
Avoids difficulties and has better overall reproducibility and better
Give credibility. Complete coating operation for continuous polymerization reaction system without intermediate storage
Can penetrate.

[0061]Chromium catalyst  Advantages of the above Ziegler-Natta type catalyst and better plant signal with continuous operation
The same advantages are obtained in terms of reliability. Ziegler to chrome or vice versa
Easy conversion is possible. Product quality improves to ESCR. Pro by copolymerization
Process productivity and product quality are improved by specific copolymer grades (film, wire and
And cable).

[0062]Conventional supported SiO2 / Mg / Ti Ziegler-Natta catalyst  Fewer problems with catalyst dispersion, static electricity, start-up, impurities, higher initial activity
Achieve higher catalyst yields and higher space-time yields without facing aggregation problems
To be able to Facilitates conversion to other catalyst systems. Lower promoter ratio
Is obtained with product quality optimization.

[0063]Metallocene  Applying the necessary coating to the metallocene catalyst, large-scale plant (high space-time yield and
And low residence time), the catalyst should be used easily enough with very high initial catalytic activity.
Optimized. With the system of the present invention, static problems at scale-up
, Sheeting and aggregate formation can be avoided (morphological degradation problems). Sa
Furthermore, this is a rate profile adjustment with slower activation under action on the promoter.
Enable. This provides optimal flexibility between the metallocene system and other catalyst systems.

[Brief description of the drawings]

FIG. 1 is a diagram of an apparatus for gas phase polymerization of olefins according to the present invention.

FIG. 2 is a drawing of an apparatus and method according to the present invention.

FIG. 3 is a drawing of an apparatus and method according to the present invention.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] October 4, 2000 (2000.10.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

One of the major problems encountered in fluidized bed processes for producing polyethylene and ethylene copolymers is reactor fouling (commonly referred to in the literature). In particular, the use of catalyst systems which exhibit increasingly higher activity at the start of the polymerization tends to adversely affect this fouling phenomenon. Today, this problem is exacerbated on an industrial scale where the production capacity of the polymerization reactor tends to increase, for example, with respect to industrial ethylene fluidized bed polymerization where more than 350 Mkg of polyethylene can be achieved in a single reactor each year. Getting worse.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

For example, when using a coated catalyst in a gas-phase reactor, on-line coating in a plug-flow reactor has the following general advantages independently of the catalyst system used: Dry catalyst injection only (no solvent) Α-olefin (C6)
Smooth reaction with control kinetics using no control parameters such as low monomer partial pressure and low reaction temperature (no initial particle overheating and good morphology control), 300 Mkg / year Low residence time (1 hour or less) with small reactor volume requirements (less than 0.5 m ³ ) to feed larger larger plants, plug flow reactors (6-8 continuous stirred tank reactors) Is reduced by the particle residence time control without the non-growing catalyst particles from the main reactor, with the possible additional benefit of the antistatic agent introduced during the coating process, to reduce the static charge at the time of injection in the polymerization reactor, such as metallocene. Easily reduce hot spots with highly active catalysts such as coated catalyst dispersion in a fluidized bed, speed profiling by adding a small fraction of activator Possibility to increase the final polymerization yield with better control of the gas, smooth agitation (low rotation speed), and low gas velocities which give good entrainment with low entrainment and better morphology at the end I do. The use of on-line gas-phase coating of the catalyst further allows: to modify the initial velocity profile to allow the catalyst to disperse before reaching its peak activity, thus homogenizing the velocity profile Can be coated in the gas phase to avoid catalyst modification and morphological involvement observed in slurries.Possibility to spray anti-static and catalyst activator into solution.Target melt index range with ethylene flow control and comonomer control. (
Smooth control of the initial reaction at low ethylene pressures and temperatures. There is the ability to increase final polymer yield and reduce residence time (higher reactor capacity). Cocatalyst usage and per ton・ Easier transition between Ziegler and metallocene catalysts ・ Improves plant reliability and facilitates access to large, efficient and flexible plants .

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IN , IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Morterol, Frederick, Robert , Marie, Michelle F-13960 Sausé-le-Pan, Route de la C ブ ル te Bleu, Closineuves (no address) F-term (reference) 4J011 AA01 BB02 DA06 DB17 EC00 MA19 MB01 4J100 AA02P AA03Q AA04Q AA07Q AA16Q AA17Q A19 AS02Q CA01 CA04 FA09 FA10 FA11 FA22 FA27 FA47

Claims (7)

[Claims] 1. A polymerization catalyst is introduced into a gas-phase plug flow reactor which, in the presence of at least one monomer, has at least 95% by weight of the resulting coated catalyst having an average coating yield of from 0.5 to 0.5%. A continuous gas phase coating method of a polymerization catalyst, which is subjected to polymerization conditions so as to have a coating yield of twice. 2. The method according to claim 1, wherein the plug flow reactor is a tubular reactor. 3. The process according to claim 1, wherein the plug flow reactor is slightly inclined at a downward angle formed with respect to a horizontal or horizontal baseline of 1 to 7 °. 4. The process according to claim 1, wherein the polymerization catalyst subjected to the coating process is substantially non-polymerized and not present in the coating reactor. 5. A polymerization catalyst having an average coating yield of 20 which is substantially uncoated.
5. A process according to any one of the preceding claims, which exhibits a coating yield of less than 5%. 6. A polymerization catalyst having an average coating yield of 18 which is substantially uncoated.
A process according to any one of claims 1 to 5, which exhibits a coating yield of greater than 0%. 7. (a) ethylene, (b) propylene, (c) a mixture of ethylene and propylene, (d) butene, and (e) one or more other (
An olefin monomer selected from other α-olefins mixed with a), (b), (c) and (d) is reacted in a fluidized bed reactor with a gas stream comprising at least some olefin. In the polymerization by continuous circulation in the presence of the coated polymerization catalyst under the reaction conditions in the fluidized bed in the vessel, including the introduction of the coated polymerization catalyst,
A continuous gas fluidized bed method wherein the coated polymerization catalyst is obtained by the continuous gas phase coating method according to any one of claims 1 to 6.